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Drilling wing ribs

wirejock

wirejock

Well Known Member
Hello. First I have to say thanks for all the assistance. I've found answers to most questions with the search function including most of the one below, but I still need some expert clarification.

I am prepping ribs for the wing assembly and reached the point where I need to drill for plumbing and wiring.

My plan is to stay as close to Vans design as possible. I'm a first time builder and don't feel qualified to wander too far into the deep end of the experimental pool.

Wiring will go through the Vans conduit per plan and I know where that hole goes from the Vans wing wiring pdf.

It also shows the location for the pitot through 1/4" grommets inserted into existing 7/16" holes.

However, I want to use the Dynon pitot/AOA with the Gretz mast and the SafeAir plumbing.

The system requires two holes for the plastic tubing which must be slightly smaller than the Vans aluminum tubing as the holes for the Safe Air tubing grommets are 3/8".
From a search I was able to find the recommended location for the Gretz mast to be outboard of the aileron bellcrank access panel which means all the plumbing has to pass the bellcrank mechanics.

Sorry to ramble but here's my questions (finally).
1. Can I run the SafeAir tubing through the Vans grommets? I think there will be a little slop and I don't want any rubbing through the tubing. It may be moot since the plumbing needs to go past the bellcrank. See next question.

2. If the plumbing needs to go outboard of the bellcrank, should I drill all the holes in another location and what is recommended by others who have used the same solution? Looking at plans, ribs and spar, it looks like I can use the existing plumbing hole for one line (depending on the answer to #1) and one of the tooling holes enlarged to 3/8" the SafeAir grommets. That would probably route tubing up against the web of the spar and between the bellcrank brackets. I'm not certain this is a good idea so feel free to tell me I'm nuts. I've got thick skin.

Help!
Thanks in advance
 
First, have you seen this Routing of wires and tubes in the Wing diagram on Van's site?

I drilled the .75" hole and ran the ribbed conduit for my wiring. That has worked out great and has allowed me to run additional wires, after I was flying. Leave a "pull string" in the conduit to make later upgrades easier.

As for the AoA and pitot lines, I drilled one hole and opened up the tooling hole at the base of each rib and shown in this picture:

(Click to enlarge)

Snap bushing were used to protect the AoA and Pitot lines and ProSeal was used to keep the conduit from moving and getting cut. The service loop you see in that picture was removed when I installed the wings.
 
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Just plumbed in the aoa on a completed RV7A. If I had done it earlier, I'd have run the line below the plastic SafeAir tubing, OR, I'd have installed thin walled plastic grommets -- #8s I believe -- and run them both through the same grommet .

pitot.jpg
 
Vans diagram

N941WR said:
First, have you seen this Routing of wires and tubes in the Wing diagram on Van's site?
Click to expand...

Yes. Thanks. I have it and actually started drilling the holes for the conduit run already.

FWIW I found someone did exactly what I plan to do.
Mr. Kalinsky used the exact three holes I plan to use (I think) and his write up is pretty detailed.
http://www.vansairforce.com/community/showthread.php?t=66515&highlight=pitot <see post #2>
Here is his web page on the subject. Sure hope he doesn't mind! :eek:
http://www.kalinskyconsulting.com/rvproj/pitotstatic.htm#20090528

In light of recent issues I really want to keep close to Vans plans.
I'm still open to suggestion though so please comment.
 
which bay

Yes, I like Bill's solution.
Bill, do you recall in which bay you mounted the tube hardware? Inboard of the bellcrank or outboard? I can't tell.
I'm going to enlarge the two smaller tooling holes for grommets then make the decision on routing after the skeleton is in the jig.
thanks again
 
wirejock said:
...
Bill, do you recall in which bay you mounted the tube hardware? Inboard of the bellcrank or outboard? I can't tell...
Click to expand...
It was one bay inboard of the bell crank.

That picture was taken through the access hole at the bell crank.

Any further inboard and you might put it in the prop wash, which is not a good thing. Any further outboard and you have to deal with routing things around the bell crank, whish is not a good thing. The reason I say putting it outboard of the bell crank is not a good thing is that any failure could jam the controls.

PS. Check out the simple template I made to locate the hole for the conduit. It is at top of this page of my website.
 
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hole jig

Awesome idea.
Actually I used another builder's suggestion.
I drilled one rib then took it's reverse mate and clecoed them together using the existing tooling holes. I match drilled the holes to the reverse rib.
These two served as masters to perform the same function on all the other ribs.
I will do the same using your suggestion for a third hole a bit below the others.
I wonder why Gretz would recommend it be installed in the bay outboard of the bell crank? I too was concerned about interference with the mechanical controls.
Thanks again.
 
The other problem with going outboard of the bellcrank is that is where tie-down ropes come from. More likely they push or pull on the pitot tube than if the pitot is inboard of the tie-down point.
 
wirejock said:
...I wonder why Gretz would recommend it be installed in the bay outboard of the bell crank? I too was concerned about interference with the mechanical controls.
Thanks again.
Click to expand...
My only thought on this is that with the short wing RV's, it gets the Pitot well past the prop disk, which may be an issue during a slip.

Remember, my plane is a -9, which has longer wings that your -7. I located the pitot in the same bay that Van's recommends, only it butts up against the outboard rib in that bay. This picture will give you a good idea of what I'm talking about.

(Click to enlarge)
 
How do you run the .81 OD conduit?

Is there an easy way to run the Van's recommended conduit (duct nt 5/8-50) which is an OD of .81" into the .75" recommended hole?

Thanks in advance for your help!
 
RoselBoysRV said:
Is there an easy way to run the Van's recommended conduit (duct nt 5/8-50) which is an OD of .81" into the .75" recommended hole?

Thanks in advance for your help!
Click to expand...

I haven't got that far but I did try a test piece before drilling the ribs and it goes through with a little encouragement. I can tell it will be a pain to snake it through.
Maybe someone will post a trick.
 
Easiest way to pull the plastic conduit through the holes is to pull HARD. Makes a lot of noise, but no damage.

My only other comment is that using Van's PDF location for the conduit is a bit too close to the wing skin rivets that eventually have to be bucked on the bottom skin. If you have the chance, move the hole just a bit to be centered between the rivet holes. It is hard to get the bucking bar on the rivet tails where the Van's plan has you drilling the hole for the conduit.
 
That tubing is actually smaller than 0.75 in the "valleys", and will be loose in the hole once it's in. Once you get enough of the tube through the hole, grab it on both sides of the rib, stretch it as far as you can and rotate your hands as though you were pedaling a bicycle with them while simultaneously pulling in the direction you want to go. Like tying shoelaces, it's easier to demonstrate than it is to write about.

Plan on several sessions, as you WILL get tired of the noise after a while.
 
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